(1) Field of the Invention
The invention relates to a method of removing spin-on-glass residue in the fabrication of integrated circuits, and more particularly, to a method of removing spin-on-glass residue on a control wafer after spin-on-glass removal in the manufacture of integrated circuits.
(2) Description of the Prior Art
In the manufacture of integrated circuit devices, control wafers are often used to test or to calibrate various production steps. The control wafers can be recycled and used again. For example, a control wafer may comprise a layer of siloxane spin-on-glass material overlying a silicon semiconductor substrate. To recycle the control wafer, the spin-on-glass layer is removed by dipping the wafer in a hydrofluoric acid (HF) solution. After the HF dip, a silk-like residue remains on the substrate surface. Further HF dip steps or plasma ashing cannot remove this residue resulting in the scrapping of the control wafer.
U.S. Pat. No. 5,679,211 to Huang discloses an oxygen-containing plasma treatment to remove a polymer formed on a spin-on-glass layer by the process of etching the spin-on-glass layer. U.S. Pat. No. 4,465,549 to Ritzman teaches the use of a Caro's acid cleaning to remove organic materials such as adhesive residue from a silicon wafer surface.